The present invention relates to a veneer for veneering of especially or relatively sharply curved surfaces and to a process for producing the veneer. More particularly, the present invention relates to a veneer comprising visible-side face veneer formed from thin veneer sheets butted against one another and adhesively bonded along edges thereof so as to be butted flush in a joint region and, on a side opposite a visible side, to a carrier material arranged underneath, an adhesive coated on underneath the veneer sheets and selected to be influenceable in a setting reaction which is reactive over a predetermined timespan. The present invention also relates to a process comprising the steps of butting the veneer sheets flush against one another along common edges thereof onto the carrier material to form a face veneer, fixing the veneer sheets in position and adhesively bonding the veneer sheets to the carrier material, with adhesive, which is selectable to be influenceable in setting reaction, remaining flexible, even after the bonding connection of the veneer sheets to the carrier material, and still remaining reactive for a predetermined timespan.
DE 4,135,658 A1 describes a process for producing a veneer, particularly a fine-wood veneer. The veneer is formed by a carrier material, for example a nonwoven consisting of polyester fibers, on which a veneer material is adhesively bonded. To allow the veneer to remain more flexible when the veneer material is bonded, so that, among other things, curved surfaces can be veneered in a simple way, the veneer material is first bonded to the carrier material at low temperatures before the adhesive has hardened completely. The advantage of this approach is that veneers of this type can be stored for several days or weeks without the adhesive setting. As a result, in terms of its setting reaction, the adhesive is still reactive over this timespan. The final setting or hardening of the adhesive takes place at temperatures and at a pressure which are increased in relation to normal conditions.
In order to save material and to some extent also weight, attempts have recently been made to assemble the face veneer from thin veneer sheets, the sheet thickness of which is smaller than 0.5 mm, in particular approximately 0.2 mm. For this purpose, one edge of a veneer sheet is butted flush against the edge of the adjacent veneer sheet and is bonded to the carrier material. The bonding of the veneer sheets has hitherto been carried out by bonded-on taping paper or by a thread of glue deposited in zigzag form. H/wever, in these thin veneer sheets of small sheet thickness (i.e., smaller than 0.5 mm, especially approximately 0.2 mm), the thread of glue or the taping paper, but also the structure of the carrier material, forms a contrast on the visible side of the veneer. Consequently, veneers produced in this manner are unacceptable due to their poor surface quality on the visible side. Contrasts, especially elevations, of the type mentioned cannot be sanded out in such thin-layer veneers, since there is then always the risk that the veneer sheet will be sanded through. Furthermore, during, for example, the shaping of the veneer and/or during pressing for the bonding with the carrier material, the butt joints between the individual veneer sheets can also tear apart, thereby resulting in a reject.
An object of the present invention is to improve the basic veneer as well as a production process therefor, to the effect that veneers formed from thin veneer sheets can, with high reliability, also be produced with an acceptable surface quality on the visible side.
The foregoing object has been achieved in a veneer product in which the carrier material is mock veneer extending entirely over the face veneer, the adhesive in the joint region of the adjacent edges of the veneer sheets is selected to set at least reactivatably with sufficient bonding between the veneer sheets and the carrier material, and the adhesive in the remaining surface of the veneer sheets is at its most adhesive while remaining flexible and reactive. With regard to the process, the mock veneer is applied to the thin veneer sheets on a side opposite a visible side, the adhesive in the joint region sets at least reactivatably, and, in a remaining region of the veneer sheets, is first still kept flexible and reactive and only after a final application of the veneer to a surface is set at the remaining region.
The adhesive, which, in well known chemical terms, assumes a so-called B-state, hardens in the region of the joint seam of the veneer sheets with a bonding effect and in a reactivatable manner. Likewise, the flexibility and reactivity of the adhesive, applied to the remaining surface and having at most an adhesive effect, are preserved. Thus, veneers according to the present invention can be bent, while the adhesive does not form a contrast on the visible side and also the seams do not tear apart.
Because a so-called mock veneer, which can be produced, for example, from a cheap wood and/or a plurality of layers of wood veneer, is used as a carrier material, no disturbing contrasts on its surface structure occur on the visible side of the veneer.